Mordenites are known to catalyse the carbonylation of feedstocks such as methanol and dimethyl ether with carbon monoxide to produce methyl acetate and/or acetic acid products. For use as catalysts in carbonylation processes, mordenites can be used in a number of different forms, including the proton form and metal modified forms.
Techniques for the preparation of metal modified forms of mordenite, such as slurry impregnation or ion-exchange are well-known. For example, WO 2009/077743 describes the loading of mordenite with a Group IB metal by the techniques of ion-exchange and slurry impregnation. WO 2010/067043 describes the preparation of mordenite catalysts by compositing a mordenite which has been pre-loaded with at least one of copper and silver, with an inorganic oxide binder.
The activity of mordenite catalysts, for the carbonylation of methanol and/or dimethyl ether to produce acetic acid and/or methyl acetate decreases as the run time increases and the catalysts then have to be regenerated. Regeneration processes are, for example, described in WO 2009/077745 and WO 2009/077739.
WO 2009/077745 describes a regeneration process wherein a mordenite catalyst is regenerated by contacting the catalyst with a molecular-oxygen containing gas and an inert diluent at a pressure of 1 to 100 bar whilst maintaining the catalyst at a temperature of 225 to 325° C.
WO2009/077739 describes a regeneration process wherein a zeolite catalyst is regenerated by contacting the catalyst with hydrogen or a mixture of hydrogen and carbon monoxide at a temperature in the range 250 to 600° C.
However, the regeneration process, and especially when repeated a number of times, can have an adverse effect on space time yield and catalyst lifetime.